From http://www.efiexpress.com/catalog/article_info.php?articles_id=1
3) Run Wideband Harness and Terminate Pins:
The 5 pin connector is supplied unterminated to make it easier to pass through the firewall of your car. There is a rubber grommet on the passenger side of the car where the factory wiring harness comes through the vehicle. Using a coat hanger, push one end through the grommet until you can grab the other end from the engine bay. Inside the car wrap/tape the wires to the coat hanger and “fish” them through the firewall.
The wires should be terminated in the LSU wideband connector as follows. Remember to route the wires through the rubber boot on the LSU connector first!
Black -> Pin 1
Orange -> Pin 4
Purple -> Pin 5
White -> Pin 6
Pin 3 should already be connected to a harness that ends in a 2 pin plug. This plug should be plugged into the 2 pin connector going to the stock narrowband oxygen sensor heater. Pin 2 is not used. After all the pins are in place, push on the purple tab that is visible through the slot on the side of the LSU connector. This will 'lock' the pins in place.
When finished, just plug the LSU connector into a wideband sensor and plug the 5 pin flat connector into the VEMS ECU. Note that a wideband sensor is not required for proper operation of the ECU.
At this stage you are ready to plug the ECU into the factory wiring harness. Remember to hook up the vacuum hose!
- What I understand
Pin --> Wire
1 --> Black
2 --> Empty
3 --> NB Sensor Heater Pin
4 --> Orange
5 --> Purple
6 --> White